It's simple. You go to the store and get a giant bottle of rubbing alcohol. Then go and pick up a big bottle of giant granule sea salt.

Add both to your tube and shake viciously. The salt will help rub the resin off the inside and the alcohol will turn brown. Excess resi is easily wiped out with towels after a couple rounds of alcohol + salt. You can get your pipes almost brand spanking new with a little bit of effort. And don't waste your money on 420 solution or whatever they are selling upcharged nowadays.